TRENTON — In ruling against a mother who left her toddler strapped in a car seat while she shopped, a state appeals court said today that leaving a young child alone in a vehicle — even briefly — is abuse or neglect.

The case originated in 2009 when the woman, identified in court papers only by the pseudonym Eleanor, left her car running with her sleeping 19-month-old inside for five to 10 minutes while she shopped for party supplies at the Middlesex Mall in South Plainfield.

By the time she returned to the vehicle, the police had arrived and the mother of four was arrested.

“A parent invites substantial peril when leaving a child of such tender years alone in a motor vehicle that is out of the parent’s sight, no matter how briefly,” Judge Clarkson Fisher Jr. wrote for the three-judge panel.

He cited the risk of “car theft or kidnapping” and the possibility that “on a hot day, the temperature inside a motor vehicle can quickly spike to dangerously high levels, just as it may rapidly and precipitously dip on a cold night.”

New Jersey’s law defining child abuse or neglect says parents must exercise “a minimum degree of care” and avoid risky situations that could harm their children or impair their “physical, mental or emotional condition.”

Fisher, citing a state Supreme Court decision from 1999, wrote that abuse or neglect happens when a parent is aware of a dangerous situation but “fails adequately to supervise the child or recklessly creates a risk of serious injury to that child.”

Eleanor’s conduct fit that description, the court found.

Eleanor’s husband vouched for her as “a good and caring” stay-at-home mom, and two of her children attested she had never left them alone. State officials should have considered that the Middlesex Mall was an “upscale” shopping locale when evaluating whether she was negligent, her attorney argued.Is leaving your child in a car unattended abuse or neglect?

“Even the most upscale of neighborhoods and shopping centers are troubled by crime ... (and) the health risks of leaving a young child in an unattended motor vehicle no doubt produce more deaths or greater injuries than those caused by criminals,” the court said.

The ruling, which can be applied to similar cases from now on, does not specify the age at which it no longer becomes negligent to leave a child in a car. Anyone under 18 is protected by the state child abuse law, but Fisher’s ruling also speaks of the “tender” age of Eleanor’s child.

Francesca Blanco, a family law attorney in Morris County, said abuse and neglect cases are usually thorny and require close analysis by the courts. Setting an age limit for leaving children in cars could create some confusion for parents, police officers and judges, she said.

If the court had set a specific age, “it gets a little tedious when someone is a little over or under the line,” Blanco said. “I think the age of the child is absolutely key in this case.

“I don’t know if there was a substantial risk of harm. It was five to 10 minutes. In five to 10 minutes, anything could happen anywhere,” she said.

Eleanor was originally charged with child endangerment and requested a hearing with the Department of Children and Families to weigh the evidence against her. However, the department declined the request because the fact she left her child unattended was not in dispute.

The appeals court agreed.

“Such events are apparently not as uncommon as might be hoped,” Fisher wrote. “The parties have cited no less than six fairly recent ... (cases) dealing with young children left unattended in motor vehicles."

In a similar case, a mother left her sick 2-year-old in her car while she bought medicine for the child. The woman was not found to be negligent, Fisher said, adding that other parents in similar situations might also be justified in those situations.

But in the case ruled upon today, the judges found there was no emergency to justify leaving the child in the car because “Eleanor was only purchasing items for a party, and other adults were available to watch the child at home while Eleanor ran her errand.”

Eleanor’s attorney, Daniel N. Epstein, did not respond to a request for comment.